Oyranos is a Colour Management System (CMS) on operating system level. It allows to match predictably input device colours to output device colours accross supporting applications. One goal is to make colour management useful for all users in a automated fashion and regardless of any technical knowledge. Oyranos is based one the well established ICC standard and various other specifications. System wide settings in Oyranos shall enshure consistency in a portable fashion. Oyranos will provide in the future a Colour Matching Module (CMM) framework. Users can then transparently select a desired colour engine.